Testing system in a circuit board manufacturing line for a automatic testing of circuit boards

ABSTRACT

A testing system for automatic testing of circuit boards ( 1 ) in a circuit board manufacturing line. The testing system comprises a set (I) of test modules ( 4 ) comprising a testing apparatus. Each test module comprises a horizontal module conveyor ( 5 ) for conveying a circuit board ( 1 ) into and out of the test module. The test modules are arranged in a superposed relation with respect to each other. The set (I) contains test modules differing from each other so that the testing operations performed by these test modules are different from each other. A feed device ( 6 ) has been fitted to receive circuit boards from the first line conveyor ( 3 ) and to feed them into the test modules ( 4 ).

FIELD OF THE INVENTION

[0001] The present invention relates to a testing system as defined inthe preamble of claim 1.

BACKGROUND OF THE INVENTION

[0002] The invention relates to so-called inline testing performed inconnection with a circuit board manufacturing line. On the manufacturingline, components are set and soldered on a circuit board, whereupon atesting system tests the circuit board and components in accordance witha set of predetermined instructions, such as a computer program, todetermine their electric operation. The manufacturing line comprises aline conveyor which conveys the circuit boards horizontally insuccession as a file to a testing apparatus. A conveyor comprised in thetesting system conveys the circuit board into a testing station, apositioning device stops it at the proper position and contacting meanscomprised in a testing device establish an electric contact with thecircuit board, whereupon the testing apparatus automatically carries outthe required testing operations on the circuit board. After the test,the circuit board is removed from the testing apparatus and allowed tomove further on the manufacturing line.

[0003] In prior art, a testing system is known in which a number oftesting apparatus are disposed side by side or one after the other onthe same level with the line conveyor. A problem with a system like thisis that the adjacent testing apparatuses disadvantageously increase thelength of the production line in confined industrial facilities.

[0004] The object of the invention is to eliminate the above-mentioneddisadvantages.

[0005] A specific object of the invention is to disclose a system thatis as compact as possible and occupies a small proportion of the lengthof the production line.

[0006] The system of the invention is characterized by what is presentedin claim 1.

BRIEF DESCRIPTION OF THE INVENTION

[0007] According to the invention, the testing system comprises a set oftest modules comprising a testing apparatus, each one of said testmodules comprising a horizontal module conveyor for conveying a circuitboard into and out of the test module, said test modules being arrangedin a superposed relation with respect to each other. The set containsmutually differing test modules, so that the testing operationsperformed by these modules also differ from each other. A feed devicehas been fitted to receive circuit boards from a first line conveyor andto feed them into the test modules.

[0008] The invention has the advantage that different tests can beperformed on the circuit boards within a production line lengthcorresponding to the line length required by a single test, thuspermitting more effective utilization of the floor area of theproduction plant. If the number of test modules placed one above theother in the set is n, then it is possible to implement n differenttests within the line length of a single test module.

[0009] In an embodiment of the system, the circuit board is providedwith an identification code or the like which specifies a predeterminedtesting operation to be performed on the circuit board. The systemcomprises an identifying device for identifying the identification code.The feed device has been fitted to feed the circuit board on the basisof the identification code into the one of the test modules that willperform the predetermined testing operation on the circuit board.

[0010] In an embodiment of the system, the manufacturing line comprisesa second line conveyor, whose conveying direction is the same as theconveying direction of the first line conveyor and which, as seen in theconveying direction, is disposed after the testing apparatus to receivethe circuit boards from the testing apparatus and to convey themhorizontally in succession as a file. The system comprises a receivingdevice disposed on the opposite side of the test modules in relation tothe feed device and fitted to receive circuit boards from the testmodules and to pass on the circuit boards onto the second line conveyorso that they form a successive file on it.

[0011] In an embodiment of the system, each test module in the testmodule set has been arranged to perform a test that is different fromthe test performed by any other test module in the same set.

[0012] In an embodiment of the system, the feed device has been arrangedto both feed a circuit board into the test module and receive one fromit, and the receiving device has been arranged to both receive a circuitboard from the test module and feed one into it.

[0013] In an embodiment of the system, the feed device, the receivingdevice and the test modules have been arranged to cooperate with eachother so as to pass the circuit boards successively through each testmodule in the test module set so that a number of testing procedurescorresponding to the number of test modules are performed successivelyon the circuit boards.

[0014] In an embodiment of the system, the feed device is a feedelevator moving in a vertical direction and comprising a number of firstelevator plane conveyors disposed one above the other at a distance fromeach other corresponding to the distance between the module conveyors sothat, when the first elevator plane conveyors are in alignment with themodule conveyors, the circuit boards can be moved from one conveyor ontothe other.

[0015] In an embodiment of the system, the receiving device is avertically movable receiving elevator comprising a number of horizontaltwo-way second elevator plane conveyors disposed one above the other ata distance from each other corresponding to the distance between themodule conveyors so that, when the second elevator plane conveyors arein alignment with the module conveyors, the circuit boards can be movedfrom one conveyor onto another.

[0016] In an embodiment of the system, the module conveyors are two-wayconveyors.

[0017] In an embodiment of the system, the first elevator planeconveyors and the second elevator plane conveyors are two-way conveyors.

[0018] In an embodiment of the system, the system comprises a second setof test modules comprising a testing apparatus and disposed beside thefirst set of test modules to perform tests on the circuit boards thatare different from the tests performed by the test modules of the firstset.

[0019] In an embodiment of the system, each test module in the secondset comprises a horizontal module conveyor for moving a circuit boardinto and out of the test module, the test modules of the second setbeing disposed in a superposed relation to each other and adjacently tothe test modules of the first set so that their module conveyors are inalignment with each other in immediate vicinity of each other to allowthe circuit boards to be moved directly from the module conveyor of atest module of the first set onto the module conveyor of a test modulesof the second set.

[0020] In an embodiment of the system, the feed device, the test moduleset and the receiving device have been assembled into a single unitbuilt in a common mounting frame to form a testing cell which can beincorporated in a modular manufacturing line consisting of differentcells.

[0021] In an embodiment of the system, the mounting frame comprisesguide supporters placed at a vertical distance from each other tosupport the test modules one above the other and allowing the testmodule supported by said guide supporters to be removed from andinserted into the mounting frame by a horizontal movement.

[0022] In an embodiment of the system, the test module comprises acassette-like frame box inside which the module conveyor and the testingapparatus are mounted, said frame box comprising a back wall providedwith rear connectors for the supply of electricity or the like and/orfor the transmission of control data. The mounting frame is providedwith counter-connectors so fitted that the rear connectors and thecounter-connectors are coupled when the test module is being mounted inthe mounting frame.

[0023] In an embodiment of the system, the test modules are disposedabove the level of the line conveyors.

[0024] In an embodiment of the system, the system comprises a horizontaltransit conveyor disposed below the lowest one of the test modules inthe test module set, in alignment with the line conveyor, for conveyingcircuit boards through the testing system without having them tested.

[0025] In an embodiment of the system, the mounting frame comprises acontrol gear space disposed below the test modules to accommodate thecontrol devices used to control the test modules and the feeding andreceiving elevators.

[0026] In an embodiment of the system, the feed elevator and/or thereceiving elevator comprises a vertical guide rail fixed to the mountingframe; a hoisting slide arranged to be movable along the guide rail, theelevator plane conveyors being connected to said hoisting slide oneabove the other at a fixed distance from each other; and a positioningactuator for moving and positioning the hoisting slide. The positioningactuator may consist of e.g. a pneumatic linear drive unit, a servomotor-operated screw, such as a ball screw, or a linear stepping motor.The positioning actuator may also consist of any other servo-controlledactuator having a sufficient positioning accuracy and speed of movement.

LIST OF ILLUSTRATIONS

[0027] In the following, the invention will be described in detail bythe aid of examples of its embodiments with reference to the attacheddrawings, wherein

[0028]FIG. 1 presents an axonometric oblique top view of a testing cellaccording to an embodiment of the system of the invention,

[0029]FIG. 2 presents a lateral view of the testing cell of FIG. 1,

[0030]FIG. 3 presents a section III-III through the testing cell of FIG.2,

[0031]FIGS. 4 and 5 present a test module according to an embodiment ofthe system of the invention in an axonometric oblique top view,

[0032]FIG. 6 presents a feed elevator or receiving elevator according toan embodiment of the system of the invention in an axonometric obliquetop view,

[0033]FIG. 7 presents the elevator of FIG. 6 in a partially explodedview,

[0034]FIG. 8 presents an example of the operation of the testing cellaccording to an embodiment of the system of the invention indiagrammatic lateral view,

[0035]FIG. 9 presents another example of the operation of the testingcell according to an embodiment of the system of the invention indiagrammatic lateral view, and

[0036]FIG. 10 presents a skeleton diagram of a testing cell according toanother embodiment of the system of the invention in lateral view.

DETAILED DESCRIPTION OF THE INVENTION

[0037] FIGS. 1-3 present a testing cell TC which can be installed as amodular part in a circuit board manufacturing line, designed forautomatic testing of circuit boards with components mounted on them.FIG. 3 illustrates the placement of the testing cell TC in theproduction line so that on both sides of the testing cell TC there is aline conveyor, a first line conveyor 3, which is placed before thetesting cell, i.e. on the supply side of it with respect to theconveying direction of the line, and a second line conveyor 8, which isplaced after the testing cell TC, i.e. on its receiving side relative tothe conveying direction of the line.

[0038] The starting point in the design of the testing cell TC has beenthat the length of the testing cell in the direction of the productionline should be as small as possible while the cell has a large testingcapacity. Thus, the testing cell TC described in the example has alength of only about 1 meter in the direction of the line.

[0039] The testing cell TC comprises a set of test modules 4, eachcomprising a testing apparatus. In the examples presented here, thenumber of test modules is five, but it is to be noted that the number oftest modules 4 may be higher or lower than that. The number of testmodules is not limited in any way because it does not change the lengthof the testing cell in the longitudinal direction of the productionline. There is usually always enough room in the vertical dimension inmanufacturing plants. At least some of the test modules 4 are designedto perform different tests. In an embodiment, all the test modules 4 inthe testing cell may be designed to perform mutually different tests.

[0040] Mounted inside each test module 4, of which an example is shownin FIGS. 4 and 5, is a horizontal module conveyor 5. The module conveyor5 is a conventional circuit board conveyor which supports the circuitboard by its opposite side edges. The module conveyor 5 can be adaptedto accommodate circuit boards of different widths by adjusting thedistance between the two halves of the conveyor. The module conveyor 5moves the circuit board into a testing position in the test module 4,where it can be brought into the proper position in a conventionalmanner so as to allow an electric contact to be established bycontacting means and the testing operations to be carried out. Themodule conveyor 5 receives the circuit board from the supply side A andremoves it from the test module to the opposite or exit side B. Inrelation to each other, the test modules 4 of set I are arranged oneabove the other. The conveying directions of the module conveyors 5 ofall test modules 4 are the same as the conveying direction of the line.The line conveyors 3 and 8 are plane conveyors which convey the circuitboards in a horizontal plane in succession as a file.

[0041] Among the circuit boards 1 conveyed on the circuit boardmanufacturing line, there are different circuit board types requiringdifferent testing. Therefore, the set of test modules 4 in the testingcell TC comprises test modules differing from each other, performingdifferent tests corresponding to different circuit board types.

[0042] Further, the testing cell TC comprises a feed elevator 6 locatedbetween the first line conveyor 3 and the test modules 4. The functionof the feed elevator 6 is to collect from the first line conveyor 3 thecircuit boards conveyed in succession so that they can be passed ontothe module conveyors 5 of the test modules 4.

[0043] The feed elevator 6 comprises a number of horizontal firstelevator plane conveyors 7, the number of which is six in this example.The number of elevator plane conveyors is at least equal to the numberof superposed test modules. The elevator plane conveyor 7 is aconventional circuit board conveyor which supports the circuit board byits opposite side edges. The elevator plane conveyor 7 can be adapted soas to enable it to convey circuit boards of different widths byadjusting the distance between its two halves. The elevator planeconveyors 7 are disposed one above the other, spaced by a distancecorresponding to the distance between the module conveyors 5. Theconveying direction of the first elevator plane conveyors 7 is the sameas the general conveying direction of the line. The elevator planeconveyors 7 are of a design permitting two-way operation.

[0044] The feed elevator 6 has been arranged to move the first elevatorplane conveyors 7 vertically in successive order so as to bring each oneof them into alignment with the first line conveyor 3 to allow onecircuit board at a time to be received from the first line conveyor 3onto each first elevator plane conveyor 7. Further, the feed elevator 6has been arranged to move the first elevator plane conveyors 7 so as tobring them into alignment with the module conveyors 5, and to pass thecircuit boards from the first elevator plane conveyors 7 onto the moduleconveyors 5 in preparation for a test to be performed in the testmodules 4.

[0045] The testing cell TC is also provided with a receiving elevator 9disposed on the exit side B of the test module set I, i.e. between set Iand the second line conveyor 8. The function of the receiving elevator 9is to receive the circuit boards from the module conveyors 5 of the testmodules 4 and to deliver them onto the second line conveyor 8 so thatthey form a successive file on it. If necessary, the receiving elevator9 can be used to feed circuit boards onto the module conveyors 5 of thetest modules 4, so that, in cooperation with the feed elevator 6,circuit boards can be passed successively into and out of different testmodules in desired order.

[0046] The structure of the receiving elevator 9 is identical to that ofthe feed elevator 6. The receiving elevator 9 comprises a number ofhorizontal second elevator plane conveyors 10, the number of which issix in this example. Their number is preferably at least equal to thenumber of superposed test modules. The elevator plane conveyor 10 is aconventional circuit board conveyor which supports the circuit board byits opposite side edges. The module conveyor 10 can be adapted toaccommodate circuit boards of different widths by adjusting the distancebetween the two halves of the conveyor. The second elevator planeconveyors 10 are disposed one above the other, spaced by a distancecorresponding to the distance between the module conveyors 5. Theconveying direction of the second elevator plane conveyors 10 is thesame as the conveying direction of the line conveyors 3, 8. Thereceiving elevator 8 has been arranged to receive the circuit boardsfrom the module conveyors 5, to bring the second elevator planeconveyors 9 into alignment with the second line conveyor 8 so as toallow the circuit boards to be passed from the second elevator planeconveyors 10 onto the second line conveyor 8 so that they form asuccessive file on it. The elevator plane conveyors 10 are of designpermitting two-way operation.

[0047] In the testing cell TC, the feed elevator 6, the test modules 4and the receiving elevator 9 have been put together as a unitaryassembly built into a common rack-like mounting frame 11. As can be seenfrom FIG. 3, the mounting frame 11 comprises guide supporters 12disposed at a vertical distance from each other to support the testmodules 4 one above the other. Supported by the guide supporters 12, thetest module 4 can be removed from the mounting frame 11 and insertedinto position by a horizontal movement. As is further shown in FIGS.1-3, in the testing cell TC the test modules 4 are disposed above thelevel of the line conveyors 3, 8. Mounted on the mounting frame 11 belowthe lowest one of the test modules in the test module set isadditionally a horizontal transit conveyor 17 (see FIGS. 8-10), arrangedto be in alignment with the line conveyors 3, 8. By means of the transitconveyor 17 and elevator plane conveyors 7 and 10, circuit boards can beconveyed directly through the testing system when no testing is to beperformed on them in the test modules 4. Below the transit conveyor 17there is a control gear space 18 accommodating control equipment neededto control the test modules 4 and the feed elevators 6 and receivingelevators 9 etc.

[0048] As can be seen from FIG. 3, the circuit board 1 may be providedwith an identification code or the like, defining a predeterminedtesting operation to be performed on the circuit board. Therefore, thesystem comprises an identifying device 100, which identifies theidentification code. The feed device 6 has been fitted to feed thecircuit board on the basis of the identification code into that testmodule 4 which will perform on the circuit board the testing operationpredetermined for it.

[0049]FIGS. 4 and 5 present one test module 4. The test module 4comprises a cassette-like frame box 13 with a module conveyor 5, apositioning and aligning device and contacting means together with theiractuators mounted inside it. The box 13 is provided with openings placedin the region of the opposite ends of the module conveyors 5.

[0050] As shown in FIG. 3, the frame box 13 of the test module 4comprises a back wall 14 provided with rear connectors 15 for the supplyof electricity to the test module 4 and for the transfer of controldata, among other things. The mounting frame 11 is provided withcounter-connectors 16 which are so fitted that the rear connectors 15and the counter-connectors 16 are connected together when the testmodule 4 is being mounted in the mounting frame 11.

[0051]FIGS. 6 and 7 illustrate the structure of the feed elevator 6and/or receiving elevator 9. Fixed to the mounting frame 11 is avertical guide rail 19. A hoisting slide 20 is mounted on the verticalguide rail 19 so that it can move along the guide rail. Attached to thehoisting slide 20 are elevator plane conveyors 7 or 10 at a fixeddistance from each other. A positioning actuator 21 moves the hoistingslide 20 and the elevator plane conveyors attached to it and positionsthem accurately in a predetermined manner. In the example embodimentillustrated in the drawings, the positioning actuator 21 is a pneumaticlinear drive unit (e.g. Festo Type DGPIL), whose conveying speed andabout 0.1 mm positioning accuracy are sufficient for the purpose. Thepositioning actuators 21 used may alternatively consist of any otherknown servo-controlled actuators, such as a servo-motor driven ballscrew transmission, a linear stepping motor or the like.

[0052]FIG. 8 presents a diagram visualizing the operation of a testingcell. In the example illustrated in this figure, the testing cellcomprises six test modules 4 placed one above the other, and the path ofthe circuit boards 1 passing through all the test modules is indicatedin the figure by an arrow A. The feed elevator 6, the receiving elevator9 and the test modules 4 are so controlled that they cooperate with eachother to pass all the circuit boards 1 carried on the line successivelythrough each test module 4 in the test module set, so that each circuitboard undergoes six different testing operations in succession. In thefigure, the feed and receiving elevators are in their low positions inan initial situation. The circuit boards are moved vertically by movingthe feed elevator and the receiving elevator in the vertical direction,and horizontally by moving the elevator plane conveyors and the moduleconveyors in ways not described in detail in this context.

[0053]FIG. 9 illustrates a method of using the testing cell, wherein thecircuit board 1 is provided with an identification code or the like,e.g. an optically readable bar code, which defines a predeterminedtesting operation to be performed on the circuit board. The code mayalso be an electrically readable code. For the identification of thecode, an identifying device 100 is provided, placed before the testingcell, e.g. in the region of the first line conveyor 3, to control theoperation of the feed elevator 6. The feed elevator 6 has been fitted tofeed the circuit board 1 on the basis of the detected identificationcode into the one or the ones of the test modules 4 that perform thepredetermined testing operations on the circuit board. The receivingelevator 9 is controlled in a corresponding manner. In the example, thefirst circuit board in the file needs a test which is performed in thetest module placed next above the bottommost one, and the next circuitboard in the file needs a test which is performed in the test moduleplaced next below the topmost one. The corresponding paths of movementof the circuit boards are indicated in FIG. 9 by arrows B and C. Thecircuit boards are moved vertically by moving the feed elevator and thereceiving elevator in the vertical direction, and horizontally by movingthe elevator plane conveyors and the module conveyors in ways notdescribed in detail in this context.

[0054]FIG. 10 presents a further embodiment of the testing cell TC,comprising two sets of test modules side by side, a first set I of testmodules 4 placed one above the other and designed to perform differenttests, and a second set II of test modules 4′ placed one above the otherand designed to perform different further tests on the circuit boards.Test modules 4′ comprise a horizontal module conveyor 5′ for moving acircuit board into the test module 4′ from its input side and for movingit out of the test module 4′ to the opposite or exit side of the module.The test modules 4′ of the second set II are disposed in a superposedarray in relation to each other adjacently to the test modules of thefirst set I so that their module conveyors 5, 5′ are mutually inalignment in immediate vicinity of each other. The system is soimplemented that the circuit boards 1 move simultaneously from themodule conveyors 5 of the test modules 4 of the first set I directlyonto the module conveyors 5′ of the test modules 4′ of the second setII. Although in this example only two adjacent sets of test modules arepresented, it is obvious that in the framework of the invention thenumber of adjacent sets of test modules is not limited but that morethan two sets may be provided.

[0055] The invention is not limited to the examples of its embodimentsdescribed above; instead, many variations are possible within theinventive idea defined in the claims.

1. Testing system for automatic testing of circuit boards (1) in a circuit board manufacturing line, said circuit boards (1) including different circuit board types requiring different testing, and said testing system comprising a testing apparatus (2) for performing testing operations, and said manufacturing line comprising a first line conveyor (3) for feeding circuit boards horizontally in succession as a file into the testing apparatus, characterized in that the testing system comprises a set (I) of test modules (4) comprising a testing apparatus, each one of said test modules comprising a horizontal module conveyor (5) for conveying a circuit board (1) into and out of the test module, said test modules being arranged in a superposed relation with respect to each other, and the set (I) contains test modules differing from each other so that the testing operations performed by these test modules are different from each other; and a feed device (6) fitted to receive circuit boards from the first line conveyor (3) and to feed them into the test modules (4).
 2. System as defined in claim 1, characterized in that the circuit board (1) is provided with an identification code or the like which defines a predetermined testing operation to be performed on the circuit board; that the system comprises an identifying device (100) for identifying the identification code; and that the feed device (6) has been fitted to feed the circuit board on the basis of the detected identification code into the one (4) of test modules that will perform the predetermined testing operation on the circuit board.
 3. System as defined in claim 1 or 2, characterized in that the manufacturing line comprises a second line conveyor (8), whose conveying direction is the same as the conveying direction of the first line conveyor (3) and which, as seen in the conveying direction, is disposed after the testing apparatus (2) to receive the circuit boards from the testing apparatus and to convey them horizontally in succession as a file; and that the system comprises a receiving device (9) disposed on the opposite side of the set of test modules in relation to the feed device (6), said receiving device (9) being fitted to receive circuit boards (1) from the test modules and to feed circuit boards onto the second line conveyor (8) so that they form a file on it.
 4. System as defined in any one of claims 1-3, characterized in that each test module (4) in the set of test modules has been arranged to perform a-different test than any other test module in the same set.
 5. System as defined in any one of claims 1-4, characterized in that the feed device (6) has been arranged to both feed and receive a circuit board (1) into/from the test module (4); and that the receiving device (9) has been arranged to both receive and feed a circuit board (1) from/into the test module (4).
 6. System as defined in claim 5, characterized in that the feed device (6), the receiving device (9) and the test modules (4) have been arranged to cooperate with each other so as to pass the circuit boards successively through each test module in the test module set (I) so that a number of testing operations corresponding to the number of test modules are performed successively on the circuit boards.
 7. System as defined in any one of claims 1-6, characterized in that the feed device (6) is a feed elevator (6) movable in a vertical direction and comprising a number of horizontal first elevator plane conveyors (7) disposed one above the other at a distance from each other corresponding to the distance between the module conveyors (5) so that, when the first elevator plane conveyors are in alignment with the module conveyors, the circuit boards can be moved from one conveyor onto the other.
 8. System as defined in any one of claims 3-7, characterized in that the receiving device (9) is a vertically movable receiving elevator (9) comprising a number of horizontal second elevator plane conveyors (10) disposed one above the other at a distance from each other corresponding to the distance between the module conveyors (5) so that, when the second elevator plane conveyors are in alignment with the module conveyors, the circuit boards can be moved from one conveyor onto the other.
 9. System as defined in claim 7 or 8, characterized in that the module conveyors (4) are two-way conveyors.
 10. System as defined in any one of claims 7-9, characterized in that the first elevator plane conveyors (7) and the second elevator plane conveyors (10) are two-way conveyors.
 11. System as defined in any one of claims 1-6, characterized in that the system comprises a second set (II) of test modules (4′) comprising a testing apparatus and disposed beside the first set (I) of test modules to perform a tests on the circuit boards that differ from the tests performed by the test modules (4) of the first set (I).
 12. System as defined in claim 11, characterized in that each test module (4′) in the second set (II) comprises a horizontal module conveyor (5′) for moving a circuit board into and out of the test module, and which test modules (4′) of the second set (II) are disposed in a superposed relation to each other and adjacently to the test modules of the first set (I) so that their module conveyors (5, 5′) are in alignment with each other in immediate vicinity of each other to allow the circuit boards (1) to be moved directly from the module conveyor (5) of a test module (4) of the first set (I) onto the module conveyor (5′) of a test module (4′) of the second set (II).
 13. System as defined in any one of claims 1-12, characterized in that the feed device (6), the set (I, II) of test modules (4, 4′) and the receiving device (9) have been assembled into a single unit built in a common mounting frame (11) to form a testing cell (TC) which can be incorporated in a modular manufacturing line consisting of different cells.
 14. System as defined in claim 13, characterized in that the mounting frame (11) comprises guide supporters (12) placed at a vertical distance from each other to support the test modules (4, 4′) one above the other and allowing the test module supported by said guide supporters to be removed from and inserted into the mounting frame by a horizontal movement.
 15. System as defined in any one of claims 1-14, the test module (4, 4′) comprises a cassette-like frame box (13), inside which the module conveyor (5) and the testing apparatus are mounted, said frame box comprising a back wall (14) provided with rear connectors (15) for the supply of electricity or the like and/or for the transfer of control data; and that the mounting frame (11) is provided with counter-connectors (16) so fitted that the rear connectors and the counter-connectors are coupled when the test module is being mounted in the mounting frame.
 16. System as defined in any one of claims 1-15, characterized in that the test modules (4, 4′) are disposed above the level of the line conveyors (3, 8).
 17. System as defined in claim 16, characterized in that the system comprises a horizontal transit conveyor (17) disposed below the lowest test module (4, 4′) in the test module set (I, II), in alignment with the line conveyors (3, 8), for conveying circuit boards through the testing system without having them tested.
 18. System as defined in claim 16 or 17, characterized in that the mounting frame (11) comprises a control gear space (18) disposed below the test modules (4, 4′) to accommodate control devices used to control the test modules and the feeding and receiving elevators (6, 9).
 19. System as defined in any one of claims 7-18, characterized in that the feed elevator (6) and/or the receiving elevator (9) comprises a vertical guide rail (19) fixed to the mounting frame (11); a hoisting slide (20) arranged to be movable along the vertical guide rail, the elevator plane conveyors (7, 10) being connected to said hoisting slide one above the other at a fixed distance from each other; and a positioning actuator (21) for moving and positioning the hoisting slide. 